In Mechanical Vapor Recompression (MVR) evaporators for dairy whey and skim milk concentration:
Options:
(A) Vapor boiled off from the boiling liquid is mechanically compressed to a higher pressure and saturation temperature, then condensed back in the same calandria as heating steam
(B) Vapor is vented straight into the atmosphere
(C) Live boiler steam is consumed at 10 times the normal rate
(D) Electric heaters boil the milk directly
Answer Key:
A
Step-by-Step Solution & Explanation
MVR compresses low-pressure overhead vapor using an electric turbofan or centrifugal compressor, raising its condensing temperature by $4-8^\circ\text{C}$ so its entire latent heat of vaporization is reused, achieving equivalent steam economies exceeding 30 to 50.